https://bugs.llvm.org/show_bug.cgi?id=45062
Bug ID: 45062
Summary: [SimplifyCFGPass] mergeEmptyReturnBlocks() leaves
broken callbr (asm goto) instruction.
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: pauls...@linux.vnet.ibm.com
CC: llvm-bugs@lists.llvm.org
Created attachment 23188
--> https://bugs.llvm.org/attachment.cgi?id=23188&action=edit
reduced testcase
define void @j() {
bb:
callbr void asm sideeffect "", "X"(i8* blockaddress(@j, %bb4))
to label %bb13 [label %bb4]
bb4: ; preds = %bb
ret void
bb13: ; preds = %bb
ret void
}
-> /bin/opt ./tc_callbr.ll -simplifycfg
define void @j() {
bb:
callbr void asm sideeffect "", "X"(i8* blockaddress(@j, %bb4))
to label %bb4 [label %bb4]
bb4: ; preds = %bb, %bb
ret void
}
Duplicate callbr destination!
callbr void asm sideeffect "", "X"(i8* blockaddress(@j, %bb4))
to label %bb4 [label %bb4]
in function j
LLVM ERROR: Broken function found, compilation aborted!
Since a callbr is not allowed to have duplicate labels, the %bb4 argument and
indirect label must be removed but it is not done.
Perhaps SimplifyCFG should do this, or perhaps calling BB.replaceAllUsesWith()
should take care of this with a call similar to
BB->replaceSuccessorsPhiUsesWith()?
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